The objective of this project is to understand the biophysical mechanisms associated with two discrete events during sperm transport and fertilization in the female mammal: the migration of spermatozoa through cervical mucus; and the interaction between spermatozoa and the egg investments. We will approach this by applying high-speed cinemicrography to record the detailed characteristics of sperm motility in these different environments. Human and bull spermatozoa will be studied in the cervical mucus of those species, the endocrine state of which will be monitored. Additional experiments will focus upon the plassage of inert materials (mucous plasma, microspheres) through the mucus. Rabbit spermatozoa will be studied during the approach to and penetration of the egg investments. Analysis of all experimental data will employ new mathematical models which we will develop of the hydrodynamics of these phenomena. As a consequence, information will be gained on biophysical features of sperm movement, the properties of cervical mucus and the ovum vestments, and the interaction betweeen the spermatozoa and these environments.